Motorcycles having a turbocharger are known in which exhaust gas of the engine is used as a drive source of the turbocharger. In these motorcycles, an exhaust manifold is attached to an exhaust port formed in a cylinder head and the turbocharger is attached to the exhaust manifold.
In turbochargers, usually, proper lubrication is done in such a manner that part of oil that circulates through an engine is supplied to a drive unit of the turbocharger (refer to JP-UM-B-60-36758, for example). JP-UM-B-60-36758 discloses a turbocharger lubrication structure in which oil that is pumped up from an oil pan by a pump is supplied to a turbocharger via an oil supply passage and then returned to the oil pan via an oil return passage.